The pervasive and persistent interpersonal problems of children with Attention Deficit-Hyperactivity Disorder (ADHD) are probable risk factors for the poor long-term outcomes that this population often experiences. These children are overwhelmingly rejected by their peers, a factor that is strongly predictive of poor prognosis. Yet little is known about the initial formation of peer status in children with ADHD. In particular, investigators have not determined the specific types of aggression that predict negative peer reputation for these youngsters. Also, despite producing many short-term benefits in the social arena, stimulant medication (the most prevalent treatment for ADHD) does not normalize peer status and does not produce lasting change. Thus, (a) elucidation of the specific social behaviors that characterize ADHD children and predict peer status and (b) evaluation of adjunctive interventions for the amelioration of social/interpersonal problems are high priorities for research in child and developmental psychopathology. The major aims of the proposed research are therefore to (1) understand the formation of peer reputation for ADHD children; (2) characterize the subtypes of aggressive and antisocial behavior that this group displays; (3) assess the short-term impact of stimulant medication on peer status and subcategories of aggression; (4) evaluate experimentally the effects of year-long trials of psychosocial intervention intended to enhance social behavior. Because ADHD is not a unitary syndrome, the designation of aggressive and nonaggressive subgroups of the ADHD sample will be performed. Studies of social behavior, peer status, and acute response to medication would occur in intensive summer research programs, with data obtained through sociometric assessment, observation of naturalistic interactions, and analysis of small-group environments. Normal comparison children would participate, to enhance ecological validity and allow appraisal of the clinical significance of acute treatment effects. Following the summer programs, participating ADHD children would be assigned randomly to (a) parent management intervention plus cognitive-behavioral child intervention, or (b) regular community intervention. Outcomes would include parent and teacher ratings of social behavior, parent-child interactions, and peer assessments. The overall goal is to develop means to prevent the negative course often associated with ADHD.